BRAKE CONTROL SYSTEM AND BRAKE CONTROL METHOD

Abstract

In order to achieve a good brake feeling, a brake control system includes a master cylinder which discharges pressurized operating fluid according to an operating amount of a brake operating member by a driver, a stroke simulator which is connected to the master cylinder and creates a reaction force with respect to that operation according to the operating amount of the brake operating member, and a control portion which calculates a target deceleration using hydraulic pressure in the stroke simulator. The brake control system is also provided with a master cylinder pressure sensor that measures the hydraulic pressure in the master cylinder. The control portion may also calculate the target deceleration using an estimated value of the hydraulic pressure in the stroke simulator calculated based on the measured value from the master cylinder pressure sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and further objects, features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings, wherein like numerals are used to represent like elements and wherein:

FIG. 1 is a system diagram of a brake control system according to a first example embodiment of the invention;

FIG. 2 is a representative view of the relationship between target deceleration and pedal stroke;

FIG. 3 is a flowchart illustrating a routine for calculating the target deceleration in the first example embodiment;

FIG. 4 is a view of one example of the relationship between a pedal stroke ST and a first preliminary target deceleration GST that is based on the stroke;

FIG. 5 is a view of one example of the relationship between a stroke simulator pressure PSS and a second preliminary target deceleration GSS that is based on the simulator pressure;

FIG. 6 is a view of one example of the relationship between a stroke simulator pressure PSS and a correction coefficient H according to a second example embodiment;

FIG. 7 is a flowchart illustrating a routine for calculating the target deceleration according to a third example embodiment; and

FIG. 8 is a system diagram of a brake control system according to a fourth example embodiment of the invention.

Claims

1. A brake control system comprising: a master cylinder that discharges pressurized operating fluid according to an operating amount of a brake operating member by a driver;a stroke simulator which is connected to the master cylinder and creates a reaction force with respect to that operation according to the operating amount of the brake operating member; anda control portion which calculates a target deceleration using a hydraulic pressure in the stroke simulator.

2. The brake control system according to claim 1, further comprising: a master cylinder pressure sensor that measures a hydraulic pressure in the master cylinder,wherein the control portion calculates the target deceleration using an estimated value of the hydraulic pressure in the stroke simulator that is calculated based on a measured value from the master cylinder pressure sensor.

3. The brake control system according to claim 2, wherein the control portion adjusts the target deceleration by correcting the estimated value of the hydraulic pressure in the stroke simulator.

4. The brake control system according to claim 2, wherein the control portion calculates the target deceleration using a weighted average value of a measured value from the master cylinder pressure sensor and the estimated value of the stroke simulator.

5. The brake control system according to claim 1, further comprising: a simulator pressure sensor that measures the hydraulic pressure in the stroke simulator,wherein the control portion calculates the target deceleration using a measured value from the simulator pressure sensor.

6. The brake control system according to claim 5, further comprising: a master cylinder pressure sensor that measures a hydraulic pressure in the master cylinder,wherein the control portion calculates the target deceleration based on a weighted average value of a measured value from the master cylinder pressure sensor and the measured value from the simulator pressure sensor.

7. The brake control system according to claim 6, wherein if an abnormality is detected in at least one of the master cylinder pressure sensor and the simulator pressure sensor, the control portion sets a weight for calculating the weighted average value according to the detected abnormality to mitigate an effect from the abnormality.

8. The brake control system according to claim 2, further comprising a stroke sensor for measuring a pedal stroke,wherein the control portion calculates the target deceleration using a stroke from the measured value of the pedal stroke.

9. The brake control system according to claim 8, wherein the control portion calculates the target deceleration as a weighted average value of a first preliminary target deceleration that is based on the stroke and is obtained from the measured value of the pedal stroke and a second preliminary target deceleration that is based on the simulator pressure and is obtained from the estimated value of the stroke simulator pressure.

10. The brake control system according to claim 8, wherein the control portion calculates the target deceleration as a weighted average value of a first preliminary target deceleration that is based on the stroke and is obtained from the measured value of the pedal stroke and a third preliminary target deceleration that is based on a weighted average value of the measured value of the master cylinder pressure and the estimated value of the stroke simulator.

11. A method for controlling a brake system having a master cylinder that discharges pressurized operating fluid according to an operating amount of a brake operating member by a driver, and a stroke simulator which is connected to the master cylinder and creates a reaction force with respect to that operation according to the operating amount of the brake operating member, comprising the step of calculating a target deceleration by using a hydraulic pressure in the stroke simulator.

12. The method for controlling a brake system according to claim 11, further comprising: measuring a master cylinder pressure;estimating a stroke simulator pressure from the master cylinder pressure; andobtaining the target deceleration using an estimated value of the stroke simulator pressure.

13. The method for controlling a brake system according to claim 11, further comprising: measuring a pedal stroke;estimating a stroke simulator pressure from a master cylinder pressure; andobtaining a first preliminary target deceleration based on the pedal stroke;obtaining a second preliminary target deceleration based on the stroke simulator pressure; andobtaining the target deceleration based on the first preliminary target deceleration and the second preliminary target deceleration.

14. The method for controlling a brake system according to claim 11, further comprising: adjusting the target deceleration by correcting the estimated value of the stroke simulator pressure.

15. The method for controlling a brake system according to claim 11, further comprising: measuring a pedal stroke;estimating a stroke simulator pressure from a master cylinder pressure; andobtaining a first preliminary target deceleration based on the pedal stroke;obtaining a weighted average pressure based on the measured value of the master cylinder pressure and the estimated value of the stroke simulator pressure;obtaining a third preliminary target deceleration based on the weighted average pressure; andobtaining a target deceleration based on the first preliminary target deceleration and the third preliminary target deceleration.

16. The method for controlling a brake system according to claim 15, further comprising: if an abnormality is detected in at least one of a master cylinder pressure sensor and a simulator pressure sensor, setting a weight for calculating the weighted average value according to the detected abnormality to mitigate an effect from the abnormality.

17. The method for controlling a brake system according to claim 11, further comprising: measuring a stroke simulator pressure; andobtaining the target deceleration using a measured value of the stroke simulator pressure.